The present invention relates to watch movements of the type including a frame and a gear train formed of wheel sets pivotably mounted on the frame. In this movement, a first of the wheel sets is provided with a shank for receiving a first hand, whereas a second of the wheel sets is provided with a pipe disposed coaxially with the shank and intended to receive a second hand. Practically all watches with hand displays have these features.
Their movement includes more precisely a motion work, formed of a cannon pinion, a minute wheel set and an hour wheel. This motion work ensures a division by twelve. The cannon pinion is friction mounted on a minute wheel set, completing one revolution per hour. Its end is provided with a shank onto which it is possible to drive a hand, for displaying the minutes.
The hour wheel is provided with a pipe mounted so as to rotate freely on the cannon pinion. It completes one revolution in twelve hours the same direction as the cannon pinion, and it carries a hand for displaying the hours.
The superposition of two wheel sets rotating at different speeds necessarily involves significant friction, which can, however, be accepted when the relative movements of the wheel sets are slow.
However, in certain applications, in which the rotational speed can reach one revolution per minute, for example, it is important to reduce losses through friction to a minimum.